The present invention pertains generally to tools, tool attachments and manufacture of same, and more particularly to apparatus for extending effective lengths of wrench shanks for increasing moments of applied force, and process for manufacturing of same. In the mechanical arts of repair and construction, a routineer may be expected to perform his services speedily and accurately in order to satisfy possibly waiting customers and to maintain a successful enterprise, profession or occupation with cost-effectiveness. As a result, mechanics may depend heavily on tools that provide dependability and ease of use. Often, such quality tools may represent a significant investment for the user or his employer.
A typical example of a predicament that may cause a setback, or at least may impede the progress of service work-flow, is an encounter with a fastener that may not loosen even when heavy force is applied to a wrench which is properly sized to fit the fastener. Numerous factors such as corrosion, dirt and others may make it difficult to apply sufficient force to create a moment of the force necessary to move or rotate the fastener. Increased moments of force may also be needed for tightening fasteners.
The moment of a force, as used herein, is a measure of its tendency to turn, rotate, bend or break a body about its moment axis. For example, the moment axis of a bolt may be the central axis of the bolt, and the moment of an applied force may be the tendency to turn (loosen or tighten) the bolt. The applied force may be the force a mechanic applies to a wrench. The moment of the applied force is the product of the force and the distance from the moment axis. The distance from the moment axis may be the length of the wrench. As is well known, a longer tool may provide a greater tendency to rotate a bolt. A well known example of a longer tool is a breaker bar for use with sockets. A socket with a breaker bar may loosen a bolt which may resist loosening when using a wrench such as an open-end or box-end wrench.
There are circumstances, however, where use of such a wrench may be needed, and mechanics have traditionally improvised various extensions to such wrenches to provide greater moments of applied forces by increasing the distance between the stubborn bolt and the point of force application.
A traditional solution which may be used by mechanics to overcome this type of predicament is called double-wrenching. As can be seen in FIG. 1, two wrenches, 101 and 102 are locked together in order to provide an effectively longer handle. The stubborn fastener 150 is typically inserted into the box end of wrench 101, and the mechanic applies force to the open end of wrench 102 in the direction as shown by the arrow. This technique may have some convenience because multiple wrenches may be generally close at hand and because the increased rotational moment due to the effectively longer handle for the same force applied may often result in successfully loosening the fastener.
Double-wrenching, although convenient at times, has several drawbacks. One problem is tool damage. High quality wrenches may be made from tool-steel which is very hard and durable. However, when such wrenches are locked together and heavy force is applied the hard steel of one may tend to dig into the hard steel of the other and vice versa, thereby generating nicks and pits on the precision-ground working ends. Manufacturers of quality tools may guarantee them for life, but the guarantee may become void if double-wrenching nicks are found.
Another type of tool damage which may be caused by double-wrenching is tool shaft bending. Tool shafts for wrenches are typically oblong in cross-section and are designed so that the long dimension of the oblong cross-section transfers the applied force to the work because each working end of the wrench is aligned with the long dimension of the oblong cross-section shaft. This makes wrenches very strong when force is applied to it in a correct manner. The short dimension of the oblong cross-section transfers little force because it is aligned perpendicularly to the working ends. So, the long dimension, or the thick part of the wrench shaft may easily transfer large forces reliably, while the short dimension, or the thinner part of the wrench shaft reduces the weight of the wrench and may make it more comfortable to use. However, when double-wrenching, the locked working ends result in the wrench shafts aligning in a perpendicular direction with respect their cross-sections. This means that the shaft of one wrench may be subjected to a force load that exceeds its design limits and may bend or break.
As stated earlier, quality tools may be expensive. Damaging or ruining a pricey tool for a momentary convenience may not be cost-effective.
Another drawback to using double-wrenching is that it may cause physical harm to the mechanic. As can be seen at FIG. 1, the locking of the two wrenches 101 and 102 is at best tenuous. The application of force may need to be carefully directed to maintain the locking and simultaneously loosen the bolt. At times, during application of force, the two wrenches may become unlocked causing the mechanic to forcefully ram his hand against part of the machinery. Painful injury to the mechanic often accompanies this scenario.
FIG. 2 illustrates another prior art method for extending the effective length of a wrench 101. A mechanic may search the work area for a pipe 201 that may fit over the wrench 101. If such a pipe 201 is found and the pipe 201 is strong enough to transfer the applied force, then it is likely that the fastener 150 may loosen with applied force to the pipe 201 in the direction indicated by the arrow because of the longer effective wrench length. However, it is likely that many different diameter pipes may be needed to properly fit various sizes of wrenches. A further drawback is that a wrench may need to be manually held in place in the pipe until force is applied, otherwise, the wrench may slip inside the pipe. Also, a hollow pipe may be subject to bending when force is applied because it may lack the structural geometry required for transferring an applied force.
Therefore, there is a need in the art for an apparatus which may provide for an increased distance from a moment axis to a point where force is applied so that the applied force may result in an increased moment of the force at the moment axis.